Graco EVR Instructions Manual page 24

Troubleshooting
Problem
Proportioning System
Proportioning pump does not hold
pressure when stalled
Material imbalance
Erratic pump movement
Pump output low
24
Cause
Pump piston or intake valve leaking
Inadequate flow from pump;
Pump cavitation
Obstructed fluid hose or dispense
valve; fluid hose ID too small
Worn piston valve or intake valve in
displacement pump
Inadequate feed pump pressure
Solution
1. Observe gauge to determine
which pump is losing pressure.
2. Determine in which direction the
pump has stalled by observing
which directional valve indicator
light is on.
3. Repair the valve.
Increase fluid supply to proportion-
ing pump:
• Use minimum 3/4 in. (19 mm) ID
supply hose, as short as practi-
cal
Clean inlet strainer screen
Worn pump inlet valve ball/seat or
gasket
Feed pump pressure is too low.
Adjust pressure to maintain 100 psi
(0.7 MPa, 7 bar) minimum.
Open, clear; use hose with larger ID.
See pump manual 3A0019.
Check feed pump pressure and
adjust to 100 psi (0.7 MPa, 7 bar)
minimum.
3A8565C